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Comets, remnants of the solar system's formation, exhibits partially unexplained outbursts that are closely tied to the physical structure of the nucleus. To investigate outbursts, we employed pore network modeling techniques, such as the Bower-Watson algorithm and Voronoi diagrams, to better represent the nucleus' complex porous structure and simulate gas transfer processes. We examined heat diffusion in the comet's subsurface and its influence on crystallization. The extra heat generated by crystallization can shift the crystalline front deeper into the nucleus, accelerating subsurface evaporation rates. This process results in the formation of a thicker ice mantle with reduced porosity on the surface, trapping evaporated gas in the underlying layers. As gas pressure accumulates over time, the mantle eventually succumbs to the buildup. By applying percolation theory, we identified the critical point at which trapped gas breaks through the surface, ultimately leading to a better understanding of comet outburst formation.

Photometry of eclipsing dwarf-nova EX Draconis was performed at the observatory of Astronomical Institute of the Academy of Sciences of the Czech Republic in Ondřejov and at the Astronomical Observatory on Kolonické sedlo during 63 nights. I calculated times of minimum light by two methods - the mirror method and the derivative method. The mirror method is more precise for these measurements with longer exposure time and smaller coverage of the light curve of eclipse. 53 new times of minima calculated by the mirror method and times of minima obtained from the older articles about EX Dra were included in the O-C diagram and fitted by the sine function and theoretical curve of LITE caused by an unseen third body. Period of cyclic changes for the sine function is 25 years, instead of 4 or 5 years period given in older papers.Period of the third body orbit is aproximately 17 years and its minimum mass is 53.5 Jupiter's mass. The sum of squared deviations is 5 times smaller for the LITE, which means that the LITE ilustrates the O-C diagram better. I determined the average outburst period for three observational seasons and I drew the phase curve of outburst. Finally, I calculated the short period of the light changes outside eclipse.

A great number of tourists visits each day the Fox Glacier in New Zealand and are subjected todangers such as jökulhlaups. This phenomena can occur suddenly and in a destructive way when abuilt up of water suddenly bursts and releases large amounts of water. This is well known to happen atthe near by Franz Josef Glacier which has similar settings to Fox Glacier, but sparse previous researchon the subject indicates different results of whether jökulhlaups are present or not by Fox Glacier. Thisthesis therefore aims to study the conditions for jökulhlaups at the glacier. This is done by remotesensing and field observations of the sandur in the Fox Glacier Valley, qualitative interviews andliterature studies with a comparison with Franz Josef Glacier. The results shows that there has beenjökulhlaups from an ice dammed lateral lake which is also the most likable way for jökulhlaups tohappen again, although there are other potential ways for it to happen due to the large amount of heavyrain that this region gets.

This thesis investigates the origin, sedimentological characteristics, and paleoglacial significance of large latero-frontal moraines and moraine-dammed glacial lakes and their potential to generate glacial lake outburst flood (GLOF) events in the Cordillera Blanca, Perú and Iceland. This topic is particularly important as the potential for GLOF events in high altitude regions is increasing as ongoing global climate warming causes rapid glacier recession and the growth of lakes impounded by unstable moraines. The first chapter of this thesis introduces the characteristics of moraine dammed lakes and GLOFs and provides details of the study areas in Perú and Iceland that were selected for this work (Chapter 1). Chapter 2 investigates the glacial history of the Cordillera Blanca, Perú through the compilation, mapping, and analysis of dated moraines in the region. The formation of moraines by different glaciers in the same region at approximately the same time is interpreted to indicate a period of regional climate conditions that were favourable for glacier expansion and/or equilibrium. Six stages of glacial activity are identified from this analysis, ranging in age from older than 35 thousand years (Stage 1) to modern (Stage 6). The third chapter of this thesis identifies the geomorphic and sedimentologic characteristics of a moraine-dammed supraglacial lake (Llaca Lake) in the Cordillera Blanca, Perú. The combined use of imagery collected with an uncrewed-aerial vehicle (UAV), field sedimentological observations and geomorphological mapping allowed the creation of a landsystem model that summarizes the current geomorphic and sedimentologic environment of Llaca Lake (Chapter 3). This is the first study to describe the landform-sediment assemblages in a tropical moraine-dammed supraglacial lake and provides a framework for further landsystem analysis of growing supraglacial lakes that are at risk of GLOF events. The fourth chapter of this thesis describes the sedimentary architecture of the eastern lateral moraine of Gígjökull in southern Iceland. An uncrewed-aerial vehicle was used to acquire high resolution photographs of an exposure through the lateral moraine that allowed the identification of seven lithofacies types and three lithofacies associations. Documentation of the sedimentary architecture of the eastern lateral moraine of Gígjökull enhances understanding of moraine development and the identification of areas of hydrogeological weakness that can reduce the structural integrity of the moraine. The research findings presented in this thesis utilize a glacial sedimentological and geomorphological approach to investigating the relationship between current and past glacial processes in the study areas, and the role that these processes play in determining the characteristics and stability of large ice marginal moraines that impound glacial lakes. This work also furthers our understanding of the dynamic surface processes at work in high altitude regions such as the Cordillera Blanca. Identifying and determining the relationships between current and past processes, sediments and landforms will enhance understanding of the role of large moraines damming glacial lakes in other high-altitude regions such as the Himalayas, British Columbia, Patagonia, and New Zealand and the associated risk of GLOF events. / Thesis / Doctor of Science (PhD)

Laurentide Ice Sheet outburst floods to the Gulf of Mexico have been mainly documented based on deep-sea cores, especially the megafloods, only during the last several interglacial episodes in the late Pleistocene. The paleoclimatic significance of giant sedimentary structures developed under unconfined Froude-supercritical turbidity currents in subaqueous settings is considerably under-examined. This research extensively documents >20-km-wide and 200-m-thick Plio-Pleistocene giant sediment waves for the first time on the northern Gulf of Mexico continental slope using 3D seismic data, which show waveform morphology in unprecedented detail. The results suggest that such large-scale bedforms were formed under sheet-like unconfined Froudesupercritical turbidity currents as cyclic steps, based on numerical and morphological analyses. Paleohydraulic reconstruction (e.g., flow velocity, discharge, and unit flux), in association with other evidence like geologic age, stable isotope records, and temporal rarity, points out that the responsible Froude-supercritical turbidity currents were most likely triggered by deglacial catastrophic outburst floods during the late Pliocene to early Pleistocene. These flooding events constitute, by far, the oldest record of the glacial outburst floods during the Quaternary Ice Age. The results propose that such pervasive occurrence of large-scale sediment waves are a proxy for catastrophic megaflood events

The thesis deals with hydrological conditions in a proglacial environment, focusing on the development of glacial lakes and the assessment of their susceptibility to outburst. The study site is the Adygine glacier-moraine complex located in the north-facing valley of the Kyrgyz Ridge, northern Tien Shan, Kyrgyzstan, at an altitude of 3400-4200 m a.s.l. In the past 50 years, the receding glacier allowed formation of several lakes, which form a three-level cascade and are fed by glacier meltwater. Below the glacier, there is a complex of several generations of moraines, through which the glacier meltwater is routed downstream. The aims of the work were to evaluate the development of individual lakes, their susceptibility to sudden outburst and possible triggers, to estimate the probable development of the site in the future, to analyse the hydrological regime of the lakes and to obtain basic information on the subsurface flow of water from the site to the stream. For the purposes of assessing the development of the lakes, the data obtained in the field (geodetic surveying of a shore line, bathymetric measurements), as well as satellite and aerial images were used. Fluctuation of lake water level was monitored by pressure sensors and the processing of this data allowed to analyse the hydrological...

[ES] Este trabajo estudia las contranarrativas visuales a modo de inscripciones y los borramientos que aparecen en el espacio público, durante el estallido social en Chile, iniciado el día 18 de octubre de 2019, en dos hitos del centro urbano de Santiago de Chile: Plaza Dignidad, donde se encuentra emplazada la escultura del general Manuel Baquedano y el Centro Cultural Gabriela Mistral [GAM]. El propósito se centra en la interpretación de las inscripciones, sus connotaciones y el cómo resignifican el espacio público. El capítulo 1, da cuenta de las inscripciones como contranarrativas en el espacio público, su contextualización histórica de movimientos artísticos y sociales que han sido incluidos como sustrato investigativo para la elaboración y desarrollo del presente estudio. El capítulo 2, se enfoca en el análisis de una intervención con paste-up de 11 folios realizada por el mismo autor, en los muros del Centro Cultural Gabriela Mistral (GAM) los cuales fueron intervenidos por los transeúntes, dando cuenta de una interpretación y discusión acerca de una serie de preguntas que se formulan en los folios. El capítulo 3, se centra en el análisis e interpretación de las inscripciones realizadas a la escultura del general Manuel Baquedano, en Plaza Dignidad, analizando las intervenciones y acciones de iconoclasia que se realizaron en la escultura durante el estallido social. El foco está puesto en el análisis de su materialidad, contenido icónico, imaginarios sociales y contradiscursos. El capítulo 4, se inicia con el grupo C.A.D.A, e incluye la intersección entre arte y espacio público durante la dictadura militar chilena. Sé suma al estudio, la revisión 3 colectivos y un artista que realizaron diversas intervenciones a modo de inscripciones durante el estallido social en Chile en 2019. Finalmente, en el capítulo 5 se discuten e integran los planteamientos en relación a las contranarrativas en el espacio público, y como las manifestaciones de "artivismo" aparecen y se diferencian, generando una narrativa específica durante el estallido social. / [CA] Aquest treball estudia les *contranarrativas visuals a manera d'inscripcions i els *borramientos que apareixen en l'espai públic, durant l'esclat social a Xile, iniciat el dia 18 d'octubre de 2019, en dues fites del centre urbà de Santiago de Xile: Plaza Dignitat, on està emplaçada l'escultura del general Manuel *Baquedano i el Centre Cultural Gabriela Mistral [*GAM]. El propòsit se centra en la interpretació de les inscripcions, les seues connotacions i el com resignifiquen l'espai públic. El capítol 1, dona compte de les inscripcions com *contranarrativas en l'espai públic, la seua contextualització històrica de moviments artístics i socials que han sigut inclosos com a substrat *investigativo per a l'elaboració i desenvolupament del present estudi. El capítol 2, s'enfoca en l'anàlisi d'una intervenció amb pasture-*up d'11 folis realitzada pel mateix autor, en els murs del CENTRE CULTURAL GABRIELA MISTRAL, *GAM, els quals van ser intervinguts pels transeünts, donant compte d'una interpretació i discussió sobre una sèrie de preguntes que es formulen en els folis. El capítol 3, se centra en l'anàlisi i interpretació de les inscripcions realitzades a l'escultura del general Manuel *Baquedano, en Plaza *Dignidad, analitzant les intervencions i accions de *iconoclasia que es van realitzar en l'escultura durant l'esclat social. El focus està posat en l'anàlisi de la seua materialitat, contingut icònic, imaginaris socials i *contradiscursos. El capítol 4, s'inicia amb el grup C.A.D.A, i inclou la intersecció entre art i espai públic durant la dictadura militar xilena. Sé suma a l'estudi, la revisió 3 col·lectius i un artista que van realitzar diverses intervencions a manera d'inscripcions durant l'esclat social a Xile en 2019. Finalment, en el capítol 5 es discuteixen i integren els plantejaments en relació a les *contranarrativas en l'espai públic, i com les manifestacions de *artivismo" apareixen i es diferencien, generant una narrativa específica durant l'esclat social. / [EN] This work studies the visual counternarratives in the form of inscriptions and erasures that appear in public space, during the social outbreak in Chile, which began on October 18, 2019, in two landmarks in the urban center of Santiago de Chile: Plaza Dignidad, where the sculpture of General Manuel Baquedano and the Gabriela Mistral Cultural Center [GAM] are located. The purpose is focused on the interpretation of the inscriptions, their connotations and how they give new meaning to the public space. Chapter 1, gives an account of the inscriptions as counter-narratives in the public space, its historical contextualization of artistic and social movements that have been included as a research substrate for the elaboration and development of the present study. Chapter 2 focuses on the analysis of an 11-page paste-up intervention carried out by the same author, on the walls of the GABRIELA MISTRAL CULTURAL CENTER, GAM, which were intervened by passers-by, giving an account of an interpretation and discussion about a series of questions that are formulated in the pages. Chapter 3 focuses on the analysis and interpretation of the inscriptions made on the sculpture of General Manuel Baquedano, in Plaza Dignidad, analyzing the interventions and actions of iconoclasm that were carried out on the sculpture during the social outbreak. The focus is placed on the analysis of its materiality, iconic content, social imaginaries and counter-discourses. Chapter 4 begins with the C.A.D.A group, and includes the intersection between art and public space during the Chilean military dictatorship. Be added to the study, the review of 3 groups and an artist who carried out various interventions in the form of inscriptions during the social outbreak in Chile in 2019. Finally, in chapter 5 the approaches in relation to counter-narratives in public space are discussed and integrated, and how the manifestations of "artivism" appear and differ, generating a specific narrative during the social outbreak. / Riquelme Loyola, M. (2023). Lo que aparece en la calle: contranarrativas visuales durante el estallido social en Santiago de Chile 2019, en Plaza Dignidad y en el Centro Cultural Gabriela Mistral [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/198564